1. Field of the Invention
The present invention relates to a supporting and braking assembly for a motor vehicle wheel.
2. Description of the Related Art
Floating caliper disc brakes are normally provided for the front wheels on motor vehicles. As is known, a brake of this type comprises a supporting upright; a brake disc, which is supported pivotally by the upright and is fixed and coaxial with respect to the wheel; and a brake caliper, which supports two brake pads arranged on opposite axial sides of the disc and is slidingly coupled to two studs or pins so as to float in direction parallel to the axis of the wheel when one of the two brake pads is subjected to the thrust of a hydraulically-operated actuator cylinder, which is part of the caliper.
In known solutions, the two studs are generally supported by a plate or bracket, which in turn is fixed to the aforesaid upright by means of two screws.
The need is felt to eliminate the bracket and therefore, couple the caliper directly to the upright, so as to reduce the number of components and therefore the assembly times and costs, and in order to reduce the weight and possible clearances between the caliper and the upright with respect to the solutions of the type described above.
To this end, U.S. Pat. No. 5,911,425, discloses a supporting upright aiming to meet the aforesaid need. In particular, this upright comprises a central part and two arms which extend radially outwards from the central part up to an outer edge of the brake disc. The caliper is connected to the upright by means of two pin guides so as to be guided and slide axially when the actuator cylinder is activated. The ends of the two arms indicated above are defined by guide teeth, to which the brake pads are axially slidingly coupled. Therefore, the braking forces are transferred tangentially from the brake pads directly to the guide teeth of the upright, without involving the caliper and the two studs.
The solution shown in this document is not very satisfactory, because there is a need to make the two arms of the upright with increased accuracy to ensure, in use, the desired tolerances in the coupling between the aforesaid guide teeth and the brake pads and therefore the proper operation of the brake pads.
By also implementing the tolerances planned in the project, the coupling with the guide teeth may in any event be subjected to undesired jamming, which may jeopardise the proper operation of the brake pads, or damage the anti-corrosion coating which is normally applied to the aforesaid guide teeth. Such jamming especially occurs if dust or fragments of the friction material of the brake pads get in between the guide teeth and the brake pads. Due to such jamming, for example, the brake pads might not have uniform wear on the surface thereof.